Paramagnetism – Applications, Properties, and Examples

Paramagnetism is a type of magnetism found in materials that are weakly attracted by an external magnetic field. These materials, known as paramagnets, have unpaired electrons, which give the atoms a permanent, though randomly oriented, magnetic moment. The best-known paramagnetic substances These are oxygen, aluminum, and sodium. The phenomenon of paramagnetism is crucial in medicine (MRI) and chemical analysis.

What Is Paramagnetism and What Are Paramagnetic Materials??

Paramagnetism a magnetic phenomenon in which a material becomes weakly magnetized under the influence of an external magnetic field. Unlike diamagnetic substances, paramagnets are weakly attracted across the field.

What is a paramagnet? is? It is a substance whose atoms or molecules have a permanent magnetic moment (that is, they have unpaired electrons). However, under normal conditions, in the absence of an external field, these microscopic magnets are randomly oriented, and the net magnetic moment of the entire material is zero. When a paramagnet When a particle is placed in a magnetic field, its magnetic moments partially align with the field, thereby slightly strengthening it.

Properties of Paramagnetic Materials

Paramagnetic properties are closely related to two key factors: the presence of unpaired electrons and the effect of temperature. Main properties of paramagnetic materials:

1. Weak attraction: The material is drawn into the area with a stronger magnetic field.

2. Non-permanent magnetization: Once the external magnetic field is removed, the orientation of the magnetic moments quickly returns to a random state, and the material loses its magnetization.

3. Temperature dependence (Curie's Law): Magnetic susceptibility paramagnetic (that is, the degree to which the material becomes magnetized) is inversely proportional to temperature. This means that the lower the temperature, the stronger the paramagnetic effect.

4. Low magnetic permeability: The relative magnetic permeability (μr) is slightly greater than 1 (μr > 1).

Examples of paramagnetic materials

Examples of paramagnetic materials include many well-known chemical elements and compounds:

• Oxygen (O₂): Gaseous oxygen is one of the best-known paramagnetic substances. In its liquid state, it is magnetic enough to be suspended between the poles of a powerful neodymium magnets.

• Metals: Aluminum, platinum, sodium, potassium, and magnesium.

• Chemical compounds: Iron(III) chloride, copper oxide, and many salts of transition metals and lanthanides.

Applications of Paramagnetic Materials

Although the paramagnetic effect is weak, the use of paramagnetic materials is crucial in advanced technology and scientific research. Key areas of application:

1. Medicine (MRI): Contrast agents (e.g., gadolinium compounds) are administered to patients during magnetic resonance imaging (MRI). Their paramagnetic properties They amplify the signal in the imaged tissues, improving diagnostic accuracy.

2. Magnets and electromagnets: Paramagnetic metals (e.g., aluminum) are used to manufacture structural components in strong permanent magnets (such as ferrite magnets) and electromagnets, when low weight and the absence of strong ferromagnetism are required.

3. Chemical Analysis (EPR): Paramagnetic materials are used in electron paramagnetic resonance (EPR) spectroscopy to study substances containing unpaired electrons, which is crucial in chemistry and biology.

4. Magnetic cooling: At extremely low temperatures, paramagnetic materials are used in adiabatic cooling to achieve temperatures close to absolute zero.